Adam Dugdale's second-half header gave Crewe Alexandra a narrow advantage over Southend in their League Two play-off semi-final at Gresty Road.

Following a first half of few chances, the centre-back headed in Ashley Westwood's 49th-minute free-kick to end the Southend's run of five consecutive clean sheets. It was no less than Steve Davis' side deserved as they extended their unbeaten run to 17 matches by outplaying a Southend team who recorded a league double over them this season.

Paul Sturrock's team also headed into the game in a rich vein of form, having won four of their previous five to miss out on automatic promotion by a point, but they turned in a subdued performance. Michael Timlin, Bilel Mohsni and Ryan Hall all went close as a belated rally arrived from Southend, but they emerged with nothing to take back to Roots Hall for Wednesday's second leg.

The Crewe captain, David Artell, was an absentee due to a broken bone in his foot, while their right-back Carl Martin returned from a 12-game absence to leave Billy Bodin among the substitutes and Matt Tootle deployed in an unfamiliar left-midfield role. Kane Ferdinand replaced Freddy Eastwood in Southend's only change.

Tootle made the most of his attacking license in the opening exchanges and almost got on the end of Byron Moore's dangerous eighth-minute cross, Southend full-back Sean Clohessy on hand to clear behind.

In the 23rd minute the Southend goalkeeper Cameron Belford did well to punch Powell's left-wing centre to safety as Luke Murphy's late run left him momentarily unsighted.

Southend edged their way into the contest after the half-hour and Ferdinand headed over from Hall's 41st-minute cross, but half-time arrived without Belford or his opposite number, Steve Phillips, being overly troubled.

Hall had a shot blocked following a deft outside-of-the-foot pass from Mohsni as Sturrock's men began the second period with greater intent, only to fall behind.

There appeared to be little danger when Westwood launched a speculative ball into the visitors' area, but Dugdale rose majestically to send a looping header beyond Belford into the far corner.

Crewe sought to press home their advantage, and Tootle just failed to find the decisive touch from another raking Westwood delivery. Belford produced a phenomenal save to push am Ajay Leitch-Smith effort over the bar in the 66th minute after a long clearance split the Southend defence.